ES 495 Midterm Water Quality and Health

classification by exposure route

waterborne: through ingestion of pathogens in drinking water -diarrheal disease, enteric fevers (typhoid), Hepatitis A Water-washed: accidential ingestion in the course of other activiites (results from having insufficient water for bathing and hygiene) -diarrheal, trachoma, scabies water-based: through an aquatic invertebrate host, repeated physical contact with contaminated water -guinea worm, schistosomiasis water related insect vector: insect vector that breeds in or near water -malaria, yellow fever

WAZ

weight for age compared to a global standard/avg for the population -WAZ reflects long-term health and nutritional status Global Burden of Disease study each day of diarrhea was associated with a reduced HAZ, WAZ, and WHZ score Diarrhea leads to malnutrition, malnutrition makes children vulnerable to infection

WHZ

weight for height z score (compared to a standard population and you can see where you fall) low WHZ=wasting -reflects recent and severe weight loss from acute starvation and/or severe disease -can also result from chronic conditions

how can we control spread of AMR

-appropriate antibiotic use -vaccines/therapeutics, environmental measures

Antimicrobial resistance (AMR)

-bacteria can develop defense mechanisms against antibiotics -genes coding these mechanisms can be transferred between bacteria by gene transfer -plasmids are mobilized as stress response to antibiotics and other pollutants Germs... -develop new cell processes that avoid using the antibiotic's target -change or destroy the antibiotics with enzymes -restrict access by changing the entryways or limiting the number of entryways -get rid of antibiotics using pumps -change the antibiotics target so the drug can no longer fit and do its job ANY antibiotic use can lead to antibiotic resistance

Vibrio cholerae (Cholera)

-bacteria, lives in aquatic environments Infection: ingestion of contaminated water, intermediate host (zooplankton) Effect: small intestine issues, DIARRHEA (VERY rapid), death (w/o treatment) -often found in highly crowded areas like NYC in 1800s, slums, refugee camps, areas hit with natural disasters -easily inactivated with typical disinfection approaches (chlorination, UV), not consuming undercooked shellfish Environmental reservoirs: -zooplankton, shellfish -consumption of raw/undercooked shellfish a risk factor endemic in 69 countries (Southeast Asia, Sub-Saharan Africa), ~3 million a year get it -spikes follow warm months, increases in zooplankton Treatment: ORT, IV rehydration, antimicrobials -has a vaccine now -WASH interventions help, sari filtration (removes infected zooplankton)

ways to get exposed to contaminants in water

-drinking water -natural waters (ex: beach, lake) -wastewater (wastewater irrigation, potable wastewater reuse) -aerosols

role of environment in spread of AMR

-fecal bacteria can exchange AMR genes with natural bacterial communities

transmission of waterborne pathogens

-fecal oral transmission -pathogens excreted in feces of infected individuals in large numbers, hundreds of thousands to more than billions -shedding can continue after infection ex: Norovirus excreted >50 days, 2-5% salmonella infected individuals become chronic carriers health effects of waterborne diseases: -diarrhea/gastroenteritis, typhoid fever, infectious hepatitis, poliomyelitis

health effects of water associated pathogens and chemicals

-gastrointestinal infection -typhoid fever -liver infection (hepatitis A and E) -nervous system (Polio, Guillain-Barre syndrome) -lung infections, pneumonia (legionella) -subclinical infection, malnutrition, growth faltering Chemicals: effects vary widely depending on chemical -cancers, neurologiccal and reproductive problems, CVD, blood pressure, respiratory problems, skeletal issues, immune system effects, low birth weight

factors that enable emergence and spread of AMR in bacteria

-inappropriate/heavy use of antibiotics, antibiotic residues in wastewater, inadequate sanitation, global travel

health implications of drug-resistant infections

-increased duration of illness/hospitalization, increased risk of death

soil-transmitted helminths (STH)

-intestinal worms that spend part of their life cycle in soil -Ascaris (roundworm) and trichuris (whipworm) transmitted by ingestion of embryonated ova (eggs embryonate in soil, get ingested, and hatch in the body) -hookworm transmitted by dermal penetration of larvae: eggs hatch in soil and penetrate skin, carried in bloodstream to head then lungs, mature in small intestine (they hook to intestinal walls causing blood loss) hookworm major cause of anemia in young children, heavy worm burden can cause intestinal obstruction -chronic STH infection can cause malnutrition and growth faltering Disease burdan: 1.5 billion gloablly

feces enter water systems through

-leaking sewers, septic tanks, pit latrines -open defecation (in LIC) -urban and agricultural surface runoff -leaching from solid manure storage -seepage/spills from animal waste lagoons -direct contamination by wild or domestic animals

criteria for ideal indicator organism

-present whenever enteric pathogen are present and at higher concentrations; not present when no fecal pollution -member of normal intestinal flora (always present regardless of pathogen) -longer survival time than pathogen, more resistent to inactivation than pathogen -not grow in water at faster rate than pathogens -concentration should be related to degree of fecal pollution -differentiate b/n animal and human fecal sources -measured easily and quickly -non-pathogenic -useful for all types of water Appropriate indicator depends on specific use case ex: water safe to drink? swim? fish? has water been treated? sources of contamination?

why do we need indicators

-too many pathogens to measure all of them each times -most pathogens difficult to detect/require long time -pathogens are not always there, even if fecal pollution is -pathogen concentrations in water sources often too low to detect -pathogen concentrations are variable

sources of chemicals in water systems

1) agriculture -crops (fertilizers, pesticides) -animal feeding operations 2) industry -manufacturing activities -resource extraction + production (mining, petroleum extraction) -service-related activities -pharmaceutical industry 3) water treatment and distribution (chemicals added to water, metals can corrode from plumbing materials) 4) naturally occurring (inorganic chemicals in rocks and soil, organic chemicals from breakdown of plant material)

Why is size important?

1) fate and transport in environment -larger organisms can be filtered in subsurface crypto: more common in surface waters than in groundwater viruses: commonly found in groundwater (so small can filter through sediment and porous rocks) 2) effectiveness of filtration as treatment mechanism -filtration (+coagulation) effective against larger organisms -important: is there an intermediate host? Vibrio cholerae/zooplankton, Guinea worm/copepod 3) detection -large organisms can be detected microscopy (helminths, protozoa) -smaller organisms need to be cultured (bacteria, viruses) (have to culture virus by infecting a host)

how to reduce spread of AMR

1) increase research into new antibiotics and vaccines (development challenges) 2) infection prevention and control 3) tracking and data of antimicrobial use and hotspots of resistance 4) antibiotic use and access: improve appropriate use of antibiotics, reduce unnecessary use, improve access to antibiotics, VACCINES (antibiotic become unnecessary if you don't get the disease), better rapid/cheap diagnostics 5) environment and sanitation: keep antibiotics and AMR threats from entering environment through improving sanitation and access to safe water -onsit treatment of wastewater from hospitals and pharmaceutical manufacturers -improved management of livestock waste -water, sanitation, and hygiene improvements Potential effect of WASH on AMR 1) reduce F-O transmission of AMR bacteria 2) reduce diarrhea and therefore antibiotic use

factors enabling AMR

1) indiscriminate antibiotic use (selects for drug-resistant gut microbial populations over sensitive ones, used to treat diarrhea and respiratory infections which often arnet caused by bacterial infections, use in animals) 2) antibiotics in wastewater (excreted unmetabolized, released from hospitals and pharmaceutical manufacturers) 3) human/animal waste in environment (manure fertilizer, leaching, inadequate sanitation, wastewater irrrigation)

Stages of Epidemiological Transition

1) pestilence and famine 2) receding pandemics (falling crude death rate, birth rate stays high) (communicable disease) 3) degenerative and man-made disease (starts to even out) (both chronic disease and communicable disease) 4) delayed degenerative diseases and emerging infections (chronic disease)

determinants of health risk for a given chemical

1) pollution potential 2) toxicity 3) bioaccumulation EPA has special requirements for chemicals that are persistent, bioaccumulative, and toxic health effects vary widely depending on chemical; all body systems affected (nervous, CVD, respiratory, musculoskeletal, immune, reproductive systems, pre-term birth, low birth weight) Timing of health effects: -immediate=effect from pathogens, communicable diseases -delayed=from chemicals, non-communicable diseases, chronic exposure (exception: nitrate and blue baby syndrome)

YLL (years of life lost)

A measure of how many years of expected life are lost due to premature death -The fatal burden of disease of a population; measures the burden of diease YLL = N x L N=# deaths L=life expectancy at the age when death occurs Calculatred for a given cause (illness), age, and sex

outbreak

A sudden rise in the incidence of a disease -appears suddenly, causes larger than normal number of infections -typically from a common source (or subsequently propagated) -limited to a small geographical area ex: cryptosporidium outbreak in Milwaukee, norovirus outbreaks in cruise ships

Lead in Flint, Michigan

April 2014 switched water source from Lake Huron to Flint River, which was more corrosive -immediate differences in water quality: color, smell, and taste where off -no corrosion control implemented and infrastructure was VERY old with much of the city getting water via lead service lines -Flint officials where not handling the situation and manipulated testing to fall withing federal standards, citizen science stepped in and definitively showed there was a problem -found no chlorine residual, and lead levels were exceedingly dangers, 13x federal limits for implementing corrosion control measures E. coli and total coliforms detected, THM violations (disinfection by-products, form when chlorine reacts with organic matter), legionella outbreak No chlorine residuals to fight microbacteria but once added more get formation of disinfection by-products so not cleaning the water anymore After 18 months switched back, provision of waterbottles and premixed formula

incubation periods

Bacteria: hours to a week (days) Virus: few days to month (days) Protozoa: 1-2 weeks to months (weeks) Helminths: could be years (years) duration of shedding correlates loosely with length of symptoms -can be asymptomatic shedding (norovirus), chronic asysmptomatic shedding (salmonella typhi), shedding can occur pre- and post- symptomatic illness

Pandemic

Disease that occurs over a wide geographic area and affects a very high proportion of the population -worldwide epidemic -global epidemic in multiple continents --spread by global travel ex: 2009 avian flue, cholera

structure of organism

Eu/Prokaryote Single/multicellular? viruses intracellular N/A bacteria pro single protozoa eu single helminths eu multicellular Eukaryote: have a nucleus with a membrane Prokaryote: no nucleus Size increases as you make your way down this list (aka smallest to largest, viruses --> bacteria --> protozoa --> helminths)

contribution to child diarrhea globally

GEMS (conventional methods): Rotavirus, cryptosporidium, shigella, Pathogenic E. coli (ST-ETEC) GEMS (molecular methods): rotavirus, cryptosporidium, shigella, pathogenic E. coli (ST-ETEC), campylobacter, adenovirus MAL-ED: norovirus, rotavirus, campylobacter, cryptosporitiudm, shigella, astrovirus

pathogens that cause largest diarrhea burden in children

GEMS (global enteric multicenter study) -rotavirus, cryptosporidium, shigella, ST-ETEC (enterotoxigenic E. coli), adenovirus, cammpylobacter -these 6caused majority of diarrhea cases (responsible for 78% of diarrhea cases) MAL-ED Highest attributable diarrhea burden 1st yr life: -norovirus, rotavirus, campylobacter, astrovirus, cryptosporidium 2nd year of life: -campylobacter, norovirus, rotavirus, astrovirus, shigella kids with moderate to severe diarrhea 8.5 times more likely to die than kids w/ no diarrhea -risk of death higher in kids who had lower height for age at enrollment Diarrhea responsible for 1/2 million deaths in kids under 5

drinking water

High income: Urban: -centrally treated and distributed piped water in urban settings -most systems use surface water -small systems rely on ground water Rural: -private wells, typically untreated Low income: -untreated non-piped sources (groundwater, springs, surface water) -some access to piped water (public taps/standpipes, piped water on premises)

Persistence in environment

How long a pollutant stays in the air, water, soil, or body Bacteria: enteric vs. aquatic -survival and growth of enteric bacteria depends on nutrients and temp -aquatic bacteria can survive and multiply in water Viruses: can "survive" for weeks to months but cannot multiply in environment Protozoan cysts/oocysts: highly resilient in environment but cannot multiply outside the host Ova of some helminth species can survive for months to years in the environment but need host to multiply

zoonotic transmission

Infections that are transmissible from animals to humans -results from contact with specific animals or the feces of a broad range of animal hosts -transmission in animal feces can have very high burden of disease

preventive chemotherapy

MDA: mass drug administration -used with deworming drugs because they are so prevalent in certain areas -used in areas with >20% STH prevalence WHO recommends annual or biannual deworming -can be incorporated into vaccine programs for young children EFFECTIVE, but quick reinfection b/c of ongoing environmental transmission

Pathogens

Microbes that cause disease -only small subset of microorganisms cause illness in humans -made of bacteria, viruses, protozoa, helminths Bacteria: Vibrio cholerae, salmonella, shigella, Campylobacter, pathogenic E. Coli, legionella Viruses: Rotavirus, Norovirus, Hepattis E and A, Polio virus Protozoa: Cryptosporidium, Giardia, Entamoeba histolytica, Naegleria fowleri Helminths: Soil-transmitted helminths, Guinea worm, schistosoma

timing of health effects

Pathogens: immediate -incubation period for most infections ranges from hours to weeks -long term sequalae like malnutrition = growth deficits Most susceptible to health effects are kids, elderly, immunocompromised, travelers Chemicals: delayed effect -usually seen after years of chronic exposure exception: nitrate causes blue baby syndrome

seasonality of infections, rotavirus and norovirus

Rotavirus: disease limited to winter season Norovirus: winter vomiting disease, seems to spike in winter and early spring -possibly because people are often in closer proximity to one another, staying inside because it is cold --esp because they are highly contagious and only have human hosts

Arsenic

Source: naturally present in rocks, leach into groundwater, absorbed by crops from contaminated soil and water, volcanoes, mining, pesticides -can be inhalened and ingested (way of ingestion will lead to cancers, inhalation --> lung, ingestion --> skin) Health effects: cancers (skin, lung, bladder), skin lesions, respiratory problems, neurological disorders, reproductive disorders Detected w/biomarkers: urine and blood for recent exposure, hair at the root=semi-recent exposure, nails for longer exposure Mitigation: rapidly excreeted in urine when exposure stops, so switch water sources, use a filter, use arsenic free nearby wells, oxidation, deeper tubewells (also have fewer pathogens) EPA MCGL: 0 EPA MCL and WHO GV: 10 oob (ug/L) Two forms, arsenite (reduced form) and arsenate (oxidized form), both equally harmful

herd immunity

The resistance of a group to an attack by a disease to which a large proportion of the members of the group are immune -happens through vaccines -benefits in non-vaccinated individuals who may not be able to get vaccinated b/c they are immunocomprised, allergic, religious conflicts -certain percentage of the population hits a vaccine/immunity threshold than the entire population is protected from severe outbreaks (less people catching and spreading it around)

Viruses

Viruses can only reproduce inside host cells, and they damage the cell when they do this VIRUSES GET INTO CELL -small intracellular organisms -hijack host cell to replicate -can "survive" but not multiply outside of host -enteric viruses are host-specific (human hosts only) ex: rotavirus, norovirus, polio, Hepatitis A and E Generally very persistent in environment because strong outercovering protects inside virus

GV (Guideline Values)

WHO guidelines for drinking water quality quality -based on health risk for lifetime consumption -national regulations may differ from guideline values based on what is feasible

non-communicable disease

a disease that is not transmitted by another person, a vector, or the environment -this is most often a result of lifestyle choices ex: diabetes, hypertension, CVD

communicable disease

a disease that is spread from one host to another, it is infectious in nature -700,000 deaths in 2017, 95k enteric infections, 81k of those enteric infections was diarrheal diseases

growth faltering

a term applied to infants whose weight, height, and head circumference are substantially below age-related growth norms and who are withdrawn and apathetic -stunting, low weight for age, wasting -measured with Z-scores compare to a standard population: HAZ, WAZ, WHZ stunting: small stature is an outward sign of other problems -there is variation in height naturally which are accounted for in comparison to global standard (z score) so you know if you really have a problem or not critical age window for growth faltering is first 1000 days (about 2.5 years)

epidemic

a widespread occurrence of an infectious disease in a community at a particular time -appears suddenly, causes a large number of infections in a short time, then disappears -spreads quickly, entire population exposed in short time -causes short, acute infection, then die or recover, survivors typically have immunity ex: Cholera (but can be endemic in some settings)

factors that affect indicator-pathogen correlations

ability of indicators to predict pathogen presence varies with many factors 1) resistance to environmental stress 2) transport, fate, and growth in environment 3) pathogen shedding patterns 4) presence of host populations 5) inactivation/removal through treatment 6) season

Environmental enteric dysfunction (EED)

acquired entereopathy of the small intestine, characterized by enteric inflammation, chronic malnutition (stunting), wasting, reduced vaccine efficacy -EED is seen in intestine by villous atrophy, malabsorption, 'leaky' intestine EED widespread in low income tropical countries -where food, water, and environment are commonly contaminated with feces Acquired in early childhood, peace corps workers, US soldiers in Vietnam got it (went way once returned home) --> suggests environmental cause Poor water, sanitation, and hygiene leads to infection with enteropathogens --> chronic intestinal inflammation, intestinal damage, increased intestinal permeability, malabsorption

exclusive breastfeeding

an infant's consumption of human milk with no supplementation of any type (no water, no juice, no nonhuman milk, and no foods) -aka nothing other than breastmilk (not even water) -WHO recommends 6 months of exclusive breastfeeding, and then weaning/supplementary feeding past that Multilevel protection: -breastmilk contains antibodies from mother -eliminates contaminated food and water -when continued during diarrhea, mitigates decline in nutritional status No breastfeeding leads to HUGE increase in level of relative risk of dying from pneumonia and diarrhea Exclusive breastfeeding rarely practiced MAL-ED shows exclusive breastfeeding declines to 50% of infants within first month of life, only 37% of kids <6 months globally are exclusively breastfed

persistence and growth in environment

aquatic species persistence growth in env't viruses no moderate cannot multiply outside of host bacteria V. Cholerae, legionella short depends on nutrients and temp protozoa Naeglaria fowleria moderate-long (cryptosporidium) cannot multiply outside of host helminths no moderate to very long (ascaris) part of life cycle is in env't but cannot multiply outside of host

Legionella

bacteria Symptoms: Legionnaires' disease, Pontiac Fever Legionnaires': severe pneumonia, cough, shortness of breath, fever, muscle aches Pontiac fever: milder than legionnaires', fever + muscle aches Transmission: inhalation of aerosols (small droplets of water) containing Legionella -water from showering, cooling towers (air conditioning systems), decorative fountains, hot tubs) Disease Burden: 10k cases US Hosts: Primarily human, detected in cattle Naturally present in water, found in drinking water supplies that meet regulatory standards -more prevalent in waters of higher temperatures, can colonize plumbing systems of hospitals, hotels, buildings

Salmonella typhi

bacteria Symptoms: typhoid fever (enteric fever), abdominal pain, headache, bowel rupture, shock, death) Disease Burden: 11-21 million infections/year worldwide Transmission: Fecal-oral Hosts: Humans only 2-5% can become asymptomatic chronic carriers is experiencing significant resistance to antibacterials

Campylobacter

bacteria, 26 total species Symptoms: watery/bloody diarrhea, fever, stomach cramps -C. jejuni can=autoimmune condition Guillain-Barree syndrome (immune system attacks nerves and can lead to paralysis) Disease burden: 1.5 million/yr US, endemic in low-income countries (nearly all kids have it by 12 months, Pakistan) -high campylobacter burden associated with reduced length for age (LAZ) Transmission: Fecal-oral Hosts: Human and animal hosts -avian species transmit in feces, poultry, cattle, swine, sheep -outbreaks in US from undercooked chicken and contaminated dairy

Shigella

bacterial dysentery Symptoms: Diarrhea (can be bloody), fever, stomach craps Disease Burden: 500k cases per year US, mostly kids under 5 Transmission: Fecal-oral -low infectious dose -can be transmitted person to person or by touching contaminated surfaces Hosts: Human only

index/model organism

behaves similar to a specific pathogen, type of indicator -in environment and in specific treatment process ex: E. coli for salmonella, clostridium spors for cryptosporidium oocysts

naeglaria fowleri

brain eating amoeba, free-living amoeba found in warm freshwaters Symptoms: headache, PAM (primary amoebic meningoencephalitis) Transmission: CANNOT be infected by drinking the water -enters through nose -travels to brain and destroys brain tissue -often get it trough high pressure, such as water slides or nasal irrigation with infected water (needs pressure to make it up from the nose to the brain) RARE infection with EXTREMELY HIGH case fatality can multiply and colonize distribution system pipes and premise plumbing, need to ensure there is chlorine residual in ALL parts of water distribution system

strengths and weaknesses of indicator organisms

can come from non-fecal sources, some can grow in environment, poor correlation with pathogens, cannot differentiate between human and animal feces strengths: can tell us when a pathogen is present if its an ideal indicator organism (aka present when pathogens are present, absent when fecal pollution is absent, no growth in water, similar survival/resistance as pathogens, easy to measure, non-pathogenic

effectiveness of water treatment

chlorine filtration (+coagulation) viruses moderate low bacteria high low protozoa v. low -moderate (crypto) high helminths low-moderate (ascaris) high

Dual burden of disease

co-morbidity from communicable and non-communicable diseases (being affected by more than one disease) -happens in the degenerative and man-made diseases stage of epi transition infectious agents can cause cancer -H. pylori --> stomach cancer -Hepatitis B/C --> liver cancer non-communicable disease can increase susceptibility to infections some chemicals impair immune function

Hyperepidemic

constantly present at high levels

determinants of pollution potential for a given chemical

driven by characteristics of specific chemical 1) fate and transport in the environment -advection: move with water flow -dispersion: spread by molecular diffusion 2) interphase mass transfer --> chemicals that are highly water soluble and do not sorb to soils can contaminate larger areas -water solubility -sorption (absorption and adsorption at once, basically if it sticks to things) -volatilization 3) transformation reactions --> chemicals that do not transform (degrade) can persist for longer -biotransformation by organisms -reaction with other substances

F diagram

fecal-oral disease transmission Feces can --> fluids, fields, flies, fingers/fomites --> stored food/water --> new host -fluids and fingers/fomites can skip the stored food/water step and go straight to new host bacteria with high infectious dose can multiply in food or water to reach infectious dose pathogens w/ low infectious dose can be transmitted person to person or contamination of inanimate objects (fomites)

HAZ

height for age in a standardized population (Z score) -low HAZ (more than 2 Z scores below average) = stunting -stunting is a result of suboptimal health and/or nutrition, and early exposure to disease Stunting is important because: >2.5% prevalence of short stature in a community, suggest chronic undernutrition 1.4 million child deaths annually attributable to undernutrition -increased risk of infection and death, cognitive impairment, less success in school, decreased wages in GEMS and MAL-ED study HAZ declined more rapidly in kids who had diarrhea (each day of diarrhea had a noticeable decline)

Schistosoma

helminth, intermediate host -eggs excreted in feces and uring, hatch and penetrate intermediate host -infective form penetrates human skin, migrates to liver and matures Symptoms: damage to liver, intestine, spleen, lungs, bladder, general inflammation, anemia, malnutrition (eggs become lodged) Disease burden: 240 million worldwide

Guinea worm

helminths, copepods/larvae Transmission: larvae eaten by copepods, copepods ingested by humans drinking water -larvae released when copepod dies and penetrate stomach and intestinal wall -eventually migrates to skin and upon contact with water can release >100k larvae into water body Symptoms: dermal almost eradicated (good candidate: only transmitted by drinking water, disease cannot return after last human case occurs, easily diagnosed, worms emerge in predictable time of year, eliminated successfully in other parts of world)

Process indicators

indicates effectiveness of a specific treatment process ex: coliform bacteria and chlorine residual for cholorine disinfection ex: turbidity for filtration

fecal indicator organism

indicates presence of fecal contamination -most problematic ex: coliforms and enterococci are the basis of regulations -chemical tracers (fecal sterols) -specific bacteria specific to feces (bacteroidales)

infectious dose ranking

infectious dose ex: viruses lowest norovirus: 50% risk w/ ingestion of 1 bacteria range, generally high V. cholerae: millions, shigella: few thousand protozoa: low crypto: 10-30 oocysts helminths low STH: theoretically need just 2 adults

MCLGs (Maximum Contaminant Level Goals)

level of contaminant with no adverse health effect is expected (with adequate safety margin) -non-enforceable goals based solely on health risks

MCLs (Maximum Contaminant Levels)

max levels of a particular contaminant there can be in the water -set as close to the MCLGs as possible Considerations: costs/benefits, can public water systems detect and remove contaminants, are there suitable treatment technologies -enforceable regulations

coliform group

most widely used fecal indicator bacteria for water quality -total coliforms (TC) -fecal coliforms (FC) -thermotolerant coliforms (TTC) -E. coli (EC) part of normal intestinal flora of warm-blooded animals

endemic

native or confined to a particular region or people -constantly present in a population ex: rotavirus, STHs, malaria, Dengue fever

salmonella

non-typhoidal version, bacteria Symptoms: Diarrhea, fever, stomach cramps Disease burden US: 1.35 million illnesses/year Transmission: Fecal-Oral (often foodborne) Hosts: Human and Animal hosts

sporadic

occurring irregularly -infrequent and irregularly occurring disease ex: Typical diarrhea cases in the US

protozoa

one-celled organisms that are more complex than bacteria -single-celled eukaryotic (has a nucleus) parasites -"tiny animals" -found in water and the environment -complex life cycle inside host -infective form is the cyst/oocyst excreted in feces ex: cryptosporidium -giardia -entamoeba histolytica -naeglaria fowleri

Helminths

parasitic worms, worms that can colonize gastrointestinal tract or other body parts -life cycle involves time in environment/intermediate host -infective forms are ova (eggs) or larvae ex: soil-transmitted helminths (hookworm, trichuris (whipworm), ascaris (roundworm)) , guinea worm, schistosoma

eradication

pathogen eliminated worldwide -its completely gone Smallpox only disease eradicated in history, in 1980 -guinea worm and polio are close Eradication is possible when: 1) immunity can be achieved (natural immunity or vaccine) 2) only human host 3) short time from exposure to symptom onset (can't spread as much if caught early) 4) visible, easily recognized symptoms

case fatality rate

percentage of population that dies from a specific disease

mobile genetic elements

plasmids, transposons, and viruses (phages) -types of DNA that can pass resistance traits directly from germ to germ work through: 1) transduction: resistance genes can be transferred from one germ to another via phages 2) conjugation: resistance genes can be transferred between germs when they connect 3) transformation: resistance genes release from nearby live or dead germs can be picked up directly by another germ

sources of fecal contamination to environmental waters

point and non-point sources, ballast waters, urban runoff, wildlife, agricultural runoff, storm runoff, environmental reservoirs, wastewater used for irrigation, septic tanks, shedding, biosolids, latrines

cryptosporidium

protozoa Symptoms: prolonged diarrhea, self-limiting in immunocompetent patients -most at risk: immmunocompromised individuals (life-threatening, malabsorption and wasting, major cause of death in AIDs patients), kids (infections in daycare centers common) Disease burden: 750k cases per in US -leading cause of diarrhea worldwide Host: Humans and some animals Widespread in environmental waters: surface waters, recreational waters (lakes, rivers), groundwater, resilient under environmental stress HIGHLY resistant to disinfection by chlorination -thick walled oocysts protects against chlorination -need coagulation+filtration to remove from drinking water, most infrastructure does not have this feature -disinfection by ozone more effective than chlorine leading cause of outbreaks in swimming pools

Entamoeba histolytica

protozoa, amoebic dysentery Symptoms: sever dysentery, can cause abscesses in liver, lungs, brain Disease burden: 50 million cases per year globally

Giardia

protozoa, one of most common parasites in US Symptoms: diarrhea, abdominal pain, bloating, nausea, vomiting -chronic illness can lead to malabsorption Disease burden: 200 million cases globally per year 1.2 million cases in US per year Transmission: fecal-oral? Hosts: Humans and range of animal

reducing transmission of diarrhea

reducing transmission of pathogenic agents of diarrheal diseases 1) water supply and excreta disposal (healthy water supplies, improved excreta disposal facilities, education to maintain new facilities) 2) personal and domestic hygiene (hand-washing) 3) food hygiene (improved practices for preparation and storage of food) 4) control of zoonotic reservoirs (control infection from animals to humans, restrict contact) 5) fly control (control flies, restrict breeding by handling feces disposal properly)

organisms with vaccines and its effectiveness

rotavirus: high (>90%) HICs, low (<50%) LICs cholera: moderate (37-66%) typhoid fever: moderate (50-80%) poliovirus: high (>99%) hepatitis A and E: high

Lead in DC

significant lead contamination in thousands of DC homes -switched disinfectent from chlorine to chloramine in hopes of reducing THM byproduct --chloramine more corrosive than chlorine -many lead service lines -partial line replacement made things worse by disturbing it -residents pooled test results and got the media involved -CDC claimed no health effects, results skewed because many already drinking bottled or filtered water by the time appropriate testing conducted -took 4 years to realize and handle the problem

Bacteria

single-celled organisms that lack a nucleus; prokaryotes -found in water and the environment -live in/on bodies of humans and animals -perform important functions for host organisms (ex: help with digestion) -most are non-pathogenic ex: Vibrio Chloerae, shigella, legionella, campylobacter, pathogenic E. coli, salmonella Come in various shapes

size comparisons

smallest --> largest Viruses: 0.02 to 0.2 microns Bacteria: .2 to 5 microns Protozoa: 4 to 20 microns Helminth: 400 to 100 microns Comparison: width of human hair: 75 microns

norovirus

virus, gastroenteritis Symptoms: severe diarrhea, vomiting After introduction of rotavirus vaccine, norovirus became leading cause of diarrhea hospitalization in US children -across all ages, most common cause of sporadic cases and outbreaks of gastroenteritis Low infectious dose Transmission: Fecal-oral (person to person), fecal-oral indirectly through contaminated food, water, sufaces Aerosols (ingestion of aerosolized vomit) Can shed insanely huge amount per gram of stool by infected individuals, can be asymptomatic outbreaks in long-term care and healthcare facilities, restaurants/catered events, schools, daycare, cruise ships seasonal variability, most common in winter

WASH

water, sanitation, and hygiene improvements in low income countries Primary barrier: sanitation (in F-diagram stops feces from spreading into fluids, fields, flies, fingers/fomites) Secondary Barrier: water treatment, improved hygeiene (in F-diagram cuts off feces access to stored food/water, and then again stops transfer from stored food/water to new host)

available vaccines

waterborne diseases with available vaccines: -rotavirus -poliomyelitis -typhoid fever -cholera -Hepatitis E and A waterborne diseases with PIPELINE vaccines: -campylobacter -enterotoxigenic E. coli -hookworm -non-typhoidal salmonella -norovirus -shigella -schistosomiasis -paratyphoid fever

Poliovirus

waterborne virus poliomyelitis (polio, refers to paralytic disease) Highly contagious, no treatment Symptoms: 3/4 have no symptoms, 1/4 have flu-like symptoms, small number develop serious symptoms affecting brain and spinal cord -paresthesia: pins and needles in legs -paralysis -meningitis Transmission: fecal-oral (person to person), fecal oral indirectly through contaminated food, water, and surfaces -ingestion of droplets from a sneeze or cough (less common) --lives in throat and intestines of infected people Effective vaccine (99%) almost eradicated

Lead

sources: naturally in earth's crust Exposure: old infrastructure/lead pipes in water distribution systems (lead service lines), faucets, falvanized pipes, old paint, transmitted through breast milk, gasoline, cosmetics, industrial activity, old food cans Health effects: potent neurotoxin; neurological and behavioral disorders, lower IQ, stunted growth, aggression, accumulates in bones, CVD, increased blood pressure and hypertension, decreased kidney function, acute lead poisoning, death, hallucinations/delirium -no safe level for lead -accumulates in blood and bones Reduce exposure: renovate infrastructure, put a filter on water sources, corrosion control (adding orthophosphates to build protective scales, pH adjustments), public education, let water run, only cold water for drinking, regularly clean faucet's screen Vulnerable subpopulations: children, minority communities with old houses/infrastructure, children of color 13x more likely to have blood lead levels >20 ug/dL, fetuses MCLG: ZERO MCL is very low, EPA enforces a treatment technique for lead instead of MCL

fecal-oral transmission

spread of disease via eating, drinking, or licking food, water, or objects contaminated by feces -there are microorganisms in feces of infected humans and animals -those microorganisms enter water systems through human and animal fecal waste 1) Drinking water at the source (runoff into surface waters, infiltration into groundwater) 2) drinking H2O in distribution system (intrusion into water pipes) 3) drinking water stored at home (contact with contaminated hands and utensils) 4) recreational waters (wastewater discharge, combined sewer overflows, runoff, bathers) 5) wastewater (irrigation, indirect potable reuse, direct potable resuse)

infectious dose

the number of microorganisms or viruses sufficient to establish an infection Bacteria: infectious dose has large range and generally high, few thousand to millions Viruses: lowest infectious dose (1-10 infectious units) Protozoa: generally low infectious does (10-30) Helminths: generally have low infectious dose -theoretically need 2 adult worms to reproduce

YLD (years lived with a disability)

the number of years spent with disability or ill health; the non-fatal measure of burden of disease -accounts for severity and duration of disease YLD = P x DW P=# of prevalent cases of illness DW= disability weight for given illness DW reflects disease severity on a scale from 0-1 0=perfect health 1=death ex: DW for diarrhea is 0.105, but is in a range that varies with age

elimination

the removal of something -pathogen stops circulating in a given area -basically new cases/new infections stop, nobody in a given area has it anymore

DALYs (disability-adjusted life years)

the sum of years of potential life lost due to premature mortality and the years of productive life lost due to disability DALY = YLL + YLD leading causes of DALYs 1) communicable diseases -lower respiratory infections -malaria -diarrheal diseases -HIV/AIDS -tuberculosis 2) neonatal disorders

Chemical Contaminants

thousands of chemcials with potential health effects -ex: heavy metals (lead), inorganic contaminants (arsenic, nitrate, fluoride), organic contaminants (PFAS) Variety of Sources -industry -agriculture (pesticides, fertilizers) -pipes and plumbing materials -by-product of water treatment -naturally present

microbiological contaminants

unwanted microbes present on or in a substance -pathogens: microorganisms that cause disease -bacteria, viruses, protozoa, helminths

Rotavirus

virus Symptoms: severe diarrhea, leading cause of diarrhea in children worldwide -responsible for 40% of child hospitalizations from diarrhea Transmission: Fecal-oral All children worldwide have rotavirus by age of 5 Does have a vaccine, very high effectiveness in HICs, much lower in LICs